1. Field of the Invention
The present invention relates to an organic electroluminescence (EL) display panel, and more particularly to an organic EL display panel and a method for sealing the same.
2. Description of the Related Art
Recently, with a large sized tendency of a display device, request for a flat display occupied in a small space is increasing. As an example of the flat display, an EL display is receiving much attention.
The EL display is divided into an inorganic EL display and an organic EL display in accordance with its materials. Of them, the organic EL display emits light while electrons injected into an organic EL layer are combined with a hole and erased. The organic EL layer is formed between a cathode and an anode.
The organic EL display has an advantage in that it is driven at a lower voltage (for example, about 10V or less) than a voltage of a plasma display panel (PDP) or an inorganic EL display. Also, since the organic EL display has further advantages such as a wide viewing angle, high speed reactivity, and high contrast, it is used as a pixel of a graphic display, a television video display, and a surface light source. Moreover, since the organic EL display is thin and weighs light, and its color sensitivity is good, it is suitable for a next generation flat display.
However, the most serious problem in commercially using the organic EL display is that its life span is short.
The life span of the display is determined by various factors such as impurities within organic matters, interface between the organic matters and electrodes, a low crystallization temperature (Tg) of the organic matters, and oxidation of the display due to oxygen and humidity. Problems related to such factors can be solved by refinement of the organic matters, development of a material having a high crystallization temperature, and induction of an organic metal to the interface between the electrodes and the organic matters. However, it is difficult to solve the problem related to oxidation of the display due to oxygen and humidity.
Oxygen and humidity that oxidize the display may exist in the display or may externally be permeated during the fabricating process steps. Oxygen and humidity are permeated into a pinhole of the display and oxidize an organic film and metal, thereby failing to perform a light emitting function of the display.
In the related art, to solve this problem, the display is covered with a shield glass to externally cut off humidity and oxygen.
In other words, as shown in FIGS. 1a and 1b, an organic EL display provided with a glass panel 1, a first electrode 2, an organic EL layer 3, and a second electrode 4 is covered with a shield glass 5 to cut off humidity and oxygen.
The shield glass 5 is attached to a corner portion of the panel by an adhesive 6.
However, since adhesive strength of the adhesive 6 is not good for a glass panel, the adhesive 6 is detached from the panel after a constant time elapses.
If the adhesive 6 is detached from the panel, a gap occurs between the panel and the adhesive so that humidity or oxygen is permeated into the display. For this reason, a problem arises in that life span of the display is shortened.